Bonding Set I
1. NF3 and PF5 are stable molecules. Write the Lewis electron-dot formulas for these molecules. On the
basis of structural and bonding considerations, account for the fact that NF3 and PF5 are stable molecules
but NF5 does not exist.
2. (a) Draw the Lewis electron-dot structures for CO32-, CO2, and CO, including resonance structures
where appropriate.
(b) Which of the three species has the shortest C-O bond length? Explain the reason for your answer.
(c) Predict the molecular shapes for the three species. Explain how you arrived at your predictions.
3. CF4 XeF4 ClF3
(a) Draw a Lewis electron-dot structure for each of the molecules above and identify the shape of each.
(b) Use the valence shell electron-pair repulsion (VSEPR) model to explain the geometry of each of
these molecules.
4. Answer the following questions about the structures of ions that contain only sulfur and fluorine.
(a) The compounds SF4 and BF3 react to form an ionic compound according to the following
equation.
SF4 + BF3 → SF3BF4
(i) Draw a complete Lewis structure for the SF3+ cation in SF3BF4.
(ii) Identify the type of hybridization exhibited by sulfur in the SF3+ cation.
(iii) Identify the geometry of the SF3+ cation that is consistent with the Lewis structure drawn in
part (a)(i).
(iv) Predict whether the F—S—F bond angle in the SF3+ cation is larger than, equal to, or
smaller than 109.50˚. Justify your answer.
(b) The compounds SF4 and CsF react to form an ionic compound according to the following
equation.
SF4 + CsF → CsSF5
(i) Draw a complete Lewis structure for the SF5– anion in CsSF5.
(ii) Identify the type of hybridization exhibited by sulfur in the SF5– anion.
(iii) Identify the geometry of the SF5– anion that is consistent with the Lewis structure drawn in
part (b)(i).
(iv) Identify the oxidation number of sulfur in the compound CsSF5.
